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How does pitch relate to glide angle?
When flying a glider, you have a polar curve. As your speed increases beyond best glide, your glide angle gets steeper. Say you are flying at best glide, you are looking through a specific point in your canopy to the spot you would land if you maintained this glide angle until you touched down.
Now say you double your speed. Of course your glide angle would get steeper, the spot will have moved down relative to the canopy at best glide. At the new pitch, looking through a specific point in your canopy to where you would land, would this point be higher, lower or the same?
The reason I ask this question is because I’m learning to glide. When you pitch the nose down to gain speed, it feels as though you are pitching down a long way, but your glide angle doesn’t seem to be affected as much as you would expect it to be. I guess a more accurate question title might be: “How does pitch relate to the polar curve?” But I’m trying to gain intuition on how glide angle changes in relation to what you perceive in the cockpit/canopy.

One way to find out is to try it in a realistic glider sim like Condor Soaring (http://www.condorsoaring.com).

Thank you, yes I have Condor. Should be easy enough to set the trim, let it settle, note the spot and repeat.

On a powered aircraft, pitch controls airspeed, power controls altitude. On a glider, with no power, you can't do something like slow flight, where you maintain altitude at an airspeed close to stalling and a high angle of attack. When you pitch down on a glider in order to land a certain spot, you want to maintain a stabilized approach angle and airspeed. The latter is controlled with the speed brakes, which are extended as necessary to control airspeed. Once you get the hang of doing this, the sight picture from the cockpit is the same as for a powered aircraft with similar characteristics.

When you pitch the nose down to gain speed, it feels as though you are pitching down a long way

This is because the change of the cockpit angle towards the horizon is the sum of both the angle of attack and the glide path angle change.
This means that at low speed your speed changes should move the target point up when you go faster (the point is only affected by the change in glide angle while your view is affected by the sum of angle of attack and glide angle change) while at high speed, when a speed change means only very small changes in angle of attack) the target point does not move much relative to the canopy any more (but it will still move a bit up when going even faster).

How does pitch relate to the polar curve?

All you need to do is to add the angle of attack at the respective speed to the polar curve and you get the pitch angle. Like this:

The blue line is the arcsin of the ratio of sink speed to flight speed. It should not be a coincidence that it looks like the sink speed polar. To that line I added the angle of attack (red line) which shows in which direction relative to the horizon the longitudinal axis of the plane points. Since the cockpit is a bit angled down, your viewing angle should be reduced by that amount. Now it is easy to see that the angle changes a lot at the low speed end but stays almost parallel to the sink speed line at high speed. Since I assumed a zero-lift angle of attack of -2°, the red line crosses the blue one at 52 m/s.

Thank you very much. That all makes a lot of sense and I hadn't considered how pitch relation changes with airspeed which is also an important thing to consider. In practical application, I guess that while in the green section of the air speed indicator you shouldn't be too concerned about your pitch angle as the glide angle does indeed move up relative to the canopy, but above that, the pitch angle gives you a more direct indication of your glide angle. Converting 52m/s we get 101knots (187kph) which roughly coincides with the top end of the ASI green band on most modern gliders.

Pitch attitude in itself isn't the big factor, other than as a speed control tool (in gliders). It's mostly about whether or not the position of the spot on the ground you're approaching changes (moves up or down in your view) at whatever pitch attitude you're holding, when that pitch attitude is being held constant.  This is key for judging glide path on final in both gliders and power planes.
You know you are overshooting a spot on the ground (your glide is flatter than the angle that the spot represents), when, at a constant pitch attitude, the spot moves down toward the glareshield, and that you are undershooting if the spot moves up (glide is steeper).
So if you are gliding at max L/D in still air, say 30:1, and are at 500 ft agl, the spot you are heading for on the ground is 2.8 statute miles out ahead (15000 feet), and at the pitch attitude that is giving you the max L/D speed, held constant, the spot 2.8 miles ahead will stay in the same spot vertically, relative to the instrument panel.
If you lower the nose to best L/D + 20 knots when you are at 500 ft, say the speed increase drops the L/D to 20 (maybe not a very efficient glider).  You pitched down to speed up, so the spot 2.8 miles out will move up in your view because you pitched over.
The key is what happens while you are holding the new pitch attitude constant.  If your glide is now steeper because you sped up, the spot 2.8 miles away represents a shallower glide (a 30:1 glide) than your new 20:1 glide angle.  What will happen is the 2.8 mile spot moved initially up to the new position when you pitched over, then instead of stabilizing at that spot, it continues to drift up because your glide path is steeper than the one represented by the spot.
The practical application of this is that when flying on final, and the spot is the runway threshold, your indicator that you are on the proper glide path is whether or not the threshold moves up or down in your view over the nose while holding a constant speed/attitude.  If you hold a constant pitch attitude and the threshold moves down, you need to add spoiler to steepen the path, and if it moves up, you need to remove spoiler to make it shallower.  In power planes, it's the same thing, but with throttle.


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Why are the B-52 thrust levers advanced inside-out?
As I understand, the standard procedure for advancing the throttle (for take-off) is as follows:

Advance throttle to desired engine input & output (N1 & N2)
Release brakes
Gradually increase the throttle to maximum
Throughout steps 1-3 either the pilot or the co-pilot control the throttle but not both

However, in this video of a B-52 we see a rather strange way of controlling the throttle. Starting at 0:44 the pilot and co-pilot take turns advancing the throttle in an inside-out manner. What is the reason behind this? Is there really a standard procedure for advancing throttle? Or does it vary based on the aircraft?

The video shows the pilots starting the engines. The typical engine start procedure on the B-52, either engine number 4 or 5 is started first. This video shows them starting engine number 5 first. Once number 5 is running, you cross bleed air to engine 4, starting it. Once number 4 and 5 have stabilized at idle for 2 minutes, the other engines can be started. This crew chose to start 3 and 6, then 7&8 and 1&2 together.
The full engine start procedure starts on page 2-41 of the flight manual, T.O. 1B-52H-1, found here: http://www.avialogs.com/viewer/avialogs-documentviewer.php?id=15888
At the beginning of the video you can see all eight throttles are pulled back to the cutoff position and all the engine gauges (middle of instrument panel) are on their bottom pegs. Later during the takeoff roll, you can see that all the engine gauges are alive.
In this video you can see that all eight throttles are controlled in unison once the engines are started.

@jjack you must advance the throttles to start the engines, per the procedure given in T.O. 1B-52H-1. Throttles pulled all the way back are in a cutoff position that actually closes both fuel shutoff valves (spar and engine). Throttle is advanced up to a certain percentage for engine lighting then advanced to help start the engine. The throttles are advanced further to increase bleed air production for starting the remaining engines. These aren't modern engines that start automatically through FADEC control.

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Why do airlines not use direct routes?
Why do airlines use SIDs and STARs when flying IFR. Wouldn’t it be easier and make more sense for them to use direct routes (for example KDFW.KLAX instead of KDFW.L4D.ZIBIT.J5N.BUBIN.P3K.KLAX (not a real route, just an example)?

related: https://aviation.stackexchange.com/q/13428/609 and https://aviation.stackexchange.com/q/42957/609

In addition to those two, say KDFW is direct to KLAX. Where does KLAX to KDFW fly?

@simonatrcl it's still not uncommon for aircraft to fly the same route in opposite directions, they are separated by altitude.

@simonatrcl 1000 ft above or below the opposite direction traffic

Obstacles, noise, unfavorable winds... But you are right, it's simple to fly direct. Until recently it was easier to fly from one radio aid to the next. The new generation of ATC/navigation is moving back to direct and optimized routes, selected by pilots/operators rather than by ATC. See Performance-Based Navigation (PBN), which RNAV has been the precursor. This article is easier to read.

You assume that airlines always fly the published SID or STAR. That's not true though. SIDs and STARS are used in procedural control to separate arriving and departing flights. When you have radar, then you don't necessarily need the procedures to do that.
When a flight is cleared for takeoff they are assigned a SID that is relevant to its destination. After takeoff and when the flight is handed off to approach (1) controller, the controller will give a vector (heading) to the flight or direct to a point on the TMA boundary. If for any reason (see below) they intend to keep the flight on the SID the controller says proceed as cleared(2) on first contact.
For approach, the flight is assigned a STAR and when it reaches the TMA boundary, the approach controller will give them a vector and the flight will deviate from the assigned STAR. See this video from NATS  and watch the arrivals to Gatwick. Compare the trajectories to what you see in the instrument procedure maps from their website. They don't seem to follow a route looking like that

source: UK AIP chart AD 2-EGKK-7-5
They seem to go direct to the holding stacks. And after exiting holding they don't seem to follow any of these routes

source: UK AIP chart AD 2-EGKK-7-12
Compare what the charts depict with what the actual vectoring looks like.

Still frame from the NATS video on Vimeo.
Now when will a flight actually do the SID or STAR you will ask. There are several cases like for example TMAs without radar service. Normally the control is procedural in that case and that includes flying the assigned SID or STAR. Another case is during unusual circumstances like for example equipment failure (radar, communications etc.) that will make radar vectoring harder or even impossible. Noise abatement can be another reason to leave a flight on the instrument departure instead of vectoring it as these routes are designed to reduce the noise impact on nearby residents and deviating from them defeats the purpose. (Thanks Bianfable!)
It's worth noting that it's common for pilots to ask for shortcuts if that can be done legally. For example if the weather conditions are VMC an arriving flight might request a visual approach. In that case IFR is canceled and the pilot will deviate from the STAR or IAP.
During takeoff, a pilot might request direct to an en-route point and thus exit the SID. If the current controller cannot grant it (let's say no radar contact), they will ask the next controller (en-route controller) if they can grant it. If yes (the en-route radar has the flight) then the flight is handed over to en-route and they are granted the direct, exiting the SID. That might not always be the case. If for example en-route control has radar contact, but because of heavy military activity the direct cannot be given safely, then the flight stays on the SID until the end.

Notes
Links to pdfs unfortunately don't work; you need to open them manually from NATS AIS page, linked in main answer.
(1) Or departure, sometimes it's the same controller.
(2) This phraseology is used in Greece (and I hope I remember it correctly). Other jurisdictions might use something slightly different.

A "visual approach" is still IFR, in VMC.  The IFR clearance is only cancelled by request of the pilot, or more usually, by the tower on clearing the runway after landing.

@MikeBrass I don't know that. That's why I've searched it first and came up with the thread that I've linked. I will ask an Approach ATCO and I will edit the answer if I'm wrong.

Another reason for flying the full procedure could be noise abatement. E.g. Amsterdam famously has procedures that are explicitly designated as night procedures. During the day, all aircraft are vectored, but during the night strict adherence to these procedures is required because those routes were chosen to reduce the noise impact on nearby residents.

@Bianfable Excellent remark! Added to the answer. Thanks!

If the downvoter cares to explain their objections, it would make that community even better.

Historically, aircraft would navigate cross country via landmarks, by flying from landmark to landmark. These were followed by radio beacons. The distance between these was limited by the visibility range of the landmark or the radio range of the beacon. Leaving the range of the previous beacon before entering the range of the next would result in navigation by dead reckoning, by compass and clock, increasing risk of errors due to winds aloft and instrument inaccuracy. Even as instruments became more accurate, such as inertial navigation systems, inaccuracy was still present. Flying off course could take you into terrain, obstructions, or restricted airspace.
Now that most airliners can navigate by GPS, they can fly to many more standard points than just radio beacons. But there are still good reasons to fly from waypoint to waypoint rather than direct.
It helps ATC keep things in order. If you have a bunch of planes enroute flying direct, it's harder to make sure they will all stay separated. It also gives pilots points that they can use as references when reporting positions. This allows pilots to calculate fuel and time enroute expected at each waypoint to track progress, and becomes especially important in oceanic airspace where there is no radar and ATC relies on these position reports to track aircraft.
As for SIDs and STARs, the arrival and departure segments are in the busiest airspace the flight will encounter. Flights are arriving from many directions and they all want to go to the same place (or vice versa, for departures). Standard procedures allow ATC to get the aircraft sequenced and separated as they descend or climb by providing standard points, altitudes, and speeds for pilots to fly. It also helps to keep departures separated from arrivals. It's much easier to keep the aircraft separated and get them where they need to go if they are in an orderly pattern than if they are each following a different route.

Several reasons:
Sovereignty airspace - certain nations are not privy to fly aircraft through the airspace of another nation without agreements, etc.
Internal airspace - Flights are restricted from flying through certain airspace within a sovereign nation for a variety of reasons from national security to traffic separation.
Pre-established air routes - Juliette airways and Q routes have been created to provide aerial corridors allowing efficient movement of aircraft from point to point along them. It also allows for predictability and uniformity giving better traffic separation.
Efficient movement of traffic in high density terminal airspace -  Airports like Hartsfield Jackson or LAX have a LOT of airplanes arriving and departing from their airspace.  Routes to provide an expedient flow of traffic and sequencing for departures and arrivals were created in the form of DPs and STARs to do this.  They are often laid out based on empirical data of how traffic is flowing into and out of these airports aided by experience on this from ATC controllers who work these aerodromes.
Now it is possible to file a point to point IFR flight plan.  General aviation aircraft frequently do this when flying between two low traffic airports.  But if you’re flying from KHOU direct to KATL in a jet, don’t expect any love from a controller, who will probably think you’re and idiot and growl out an amended clearance along a Q route following s published DP for you to copy and fly before he’ll release you.

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Why does a jet's combustion energy propel the engine forwards rather than acting equally in all directions to create zero thrust?
I'm a novice.  I have high school physics and I've seen many explanations of how a jet engine works.   To paraphrase: Fans compress air into a chamber where combustion energy is created, which spews out the back of the engine, propels the plane forwards in a typical Newtonian action/reaction way, and also spins more fans that in turn spin the previously mentioned compressor fans.    I know that's not a precise explanation but it just serves to introduce my question.
Why does the combustion chamber not act more like, say, a hand grenade?  That is, why doesn't the energy act equally in all directions?  What makes it directional?   I have never understood this from the dozens of school-level explanations I've seen on the topic.   Why does the energy from combustion cause the "low pressure turbines" at the rear of the engine to drive the compressor blades and not the other way around?  Or the most likely scenario in my flawed understanding, why doesn't the energy act equally on all the fans in the front and back of the engine to create no net propulsion?

@Bianfable it will take me a little time to digest the answers there but I think the question is essentially the same as mine.  Not sure if I should delete this question now.

@Jay Don't worry about it, it will likely be marked as a duplicate and may help others find the relevant question.

@jay613 The short answer is "combustion doesn't begin until flow direction has already been established" - the longer answer is in that linked question and answer.  As an example, when I'd start the engines in my SH-2F helicopter (in the Navy) the compressor would already be turning at 12% rated speed (which means air flowing aft) before we introduced fuel and ingntion into the compressed, flowing air in the  combustion section. (T-58-GE-8F turboshaft engine).

@jay613, be careful to not misunderstand some points. Energy does not "act on fans" or anything else. Energy is (in my view) a very difficult concept in newtonian mechanics, and it can be seen as a quantity of the system or fluid (like air). Inside the combustion chamber, chemical energy is given to the air flow. No mechanical force act on it and as KorvinStarmast said, the flow is already established before entering in combustor.

@Acsed. thanks, that gives me more to think about.  The idea that the combustion energy is transferred to the flowing air in a somehow directional manner, and not directly to the turbines.     The details may be beyond my ability to understand, but it will help me to get past the inadequate school-level explanation.

@jay613, inside a thermal engine, we consider only two kinds of energy transfer: mechanical work and heat. During combustion, only the last is involved, and has the consequence to increase air temperature. Temperature is directly related to chemical energy or so called internat energy (which is only one type of energy..). I recognise, these are quit difficult concepts for a school level student (points are usually studied in thermodynamics at university). Nevertheless, that's really a good sign if you ask yourself these questions so early, I encourage you to continue ;)

The layperson answer is:
You are making air expand in a contained space but giving it an escape path in a particular direction that is easier to take than making the container blow up.  When I was a kid and it was possible for kids to buy firecrackers from the corner store, I used to like to make rockets out of them to propel balsa gliders.  You rolled the end of the firecracker between your fingers to make the packing fall out so it was open at one end, and taped it to your glider.  When the fuse burned down and the gun powder lit off (just after you threw the glider), the expanding gases went out the open end, making a nice rocket that ran about a second.  Close off the open end, like a normal firecracker, so the gases have nowhere to go, and it blew up (which would occasionally destroy my gliders when I didn't roll out enough of the packing - good thing they only cost a dime in 1967).
So air is being made to expand and you give it somewhere to go.  Since the front end is open as well, why it doesn't go back out the front is simply because the engine is packing in air from that direction faster and harder than the burning air can push back, relative to its fairly easy path out the tail pipe, so it takes the "easy way out" (jet engines can back flow if things go off kilter - you will sometimes see flames coming out the front during "stall/surge" events).
In taking the easy way out, it's still has to accelerate to high velocity to make it through an opening that is constricted, and there's your Newtonian thrust reaction.
The last part is, you put a windmill, a turbine, in the high velocity flow and use the windmill to drive a compressor to keep the air being packed in at the front.  You are extracting some of the energy in the flow going out the turbine section to power air-packing equipment at the other end, to keep the cycle going by itself without any external help.  Basically you are redirecting a part of the energy of the burning fuel air mixture to keep the cycle going instead of making thrust.
In a piston engine, you have a similar energy transfer effect, in a radically different format, to self-sustain the cycle. Air burns in a cylinder's combustion chamber and forces the piston down to drive a propeller, but some of that rotation energy is being used to drive the adjacent piston on its compression stroke, redirecting a part of the energy of the burning fuel air mixture to keep the cycle going instead of making torque at the prop.
The jet engine does the same thing in a linear fashion using aerodynamic forces instead of closed spaces inside cylinders, depending on the inertia and velocity of the flow (like a hallway packed with people running in one direction - forget about trying to run the other way) to channel all of the forces where they need to go to keep the cycle going.

Or match rockets.  Take a paper match, a bit of aluminum foil, and a pin.  Wrap the foil around the match head, using the pin to leave an escape nozzle along the length of the match.  Then hold a lit match under the head.  It ignites, the gasses escape out the nozzle, and your match rocket flies off.

Kids I knew used to make match rockets with multiple match heads packed into a pen barrel. They were more dangerous I think. Pack a medicine container with match heads and you have a little flashbang grenade!  I put 4 firecracker rockets on another kid's "25 center" balsa glider (the ones with the rubber band prop), 2 on the wingtips and two on the fuselage. We got all the fuses going and launched it.  It climbed to about 15 feet, then went shooo shooo shooo BANG!!!  Spun down with one wing in balsa shards. Boy was that kid mad...

The flow of gasses can be guided mechanically.  The turbine blades allow it to pass through, while the fan blades block it.
For example, take a look at the Tesla Valve in which fluid flows easily in onn direction, but is obstructed in the other direction.

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Is there an exact solution for induced velocity during vortex ring state?

In plots such as these, the section between -2 and 0 has no exact solution. As shown in the first image, the other two formulas are known, but not during vortex ring state because, as seen in the second image where the functions continue, neither match the data. After a bit of analysis, I have found that the following function is a close fit to the approximation given in the first image:
$$f(x) = \sqrt{1-\frac{x^2}{4}} + \frac{x(x^2 + x - 1)}{2}+\frac{4x^3}{x^3-8}$$
But I am not aware of any way I could even go about proving this is or is not the exact solution.
Thanks

By its nature, VRS is not constant over time or location on the rotor disk. Any estimation of induced velocity in VRS is going to be time- and/or location-averaged, this way we can use the same expressions for rotor power and so forth. Well, also in momentum theory, induced velocity is sort of averaged over the rotor disk; there are factors that account for non-uniformities in induced velocity along the rotor radius, but these are relatively simple.
The unsteady nature of VRS changes rotor geometry and this renders any estimation for exact induced velocity invalid. The change/flex in rotor geometry is significant even for one-piece rotors (think multicopters); with hinged rotors, the rotor blade dynamics need to be at the center of any analysis on induced velocity in VRS.
In my experience with a case study with Eurocopter X3, estimations for VRS work OK for high-solidity and rigid rotors; such as fixed-wing propellers in reverse thrust and the X3's propeller generating reverse thrust when the aircraft is in slow forward flight.

Oh that makes a lot of sense, very well explained thankyou


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How can the 3M22 Zircon receive commands at high speeds?
According to its Wikipedia article, the scramjet-powered 3M22 Zircon missile is capable of achieving speeds of up to Mach 9, at which a plasma may be created around the missile. The article further mentions a plasma stealth effect "absorbing any radio waves" but then goes on to say it "exchanges information in flight and can be controlled by commands". If the plasma cloud around it absorbs all radio waves, then how can it still receive commands?

Educated guess from someone not involved in plasma physics or radio technology: most likely communication with the missile happens on a part of the spectrum that penetrates plasma better, but is probably less conventional in radio communication.


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What propeller for flying slow and efficiently?
So I'm getting into R/C flying and got myself a nice, but pre-owned trainer model. One of the things that need replacing is the propeller, which is a 2-blade nylon 10x8 with too many signs of damage for my liking.
I'd like to stay with a 2-blade 10x8 to not get into any troubles with regard to overloading the motor or ESC. But there's more decisions to be made aside from number of blades, size and pitch.

symmetrical vs. undercambered?
swept-tipped vs. straight-tipped?
nylon vs. wood vs. carbon fiber?

Given that I'm just starting out here, it seems staying with a straight-tipped, symmetrical nylon prop would be the conservative choice. I'm wondering about these things though:

since the "collision object" putting the propeller blades at risk the most is the gras you land on, might carbon fiber be more durable, just cutting through it without taking any damage?
might wood and carbon sound better than nylon due to being less flexible?
might wood and carbon be more efficient than nylon due to being less flexible?
how much at-risk for unplanned rapid disassembly from just doing their jobs are these three materials in comparison to one another, a.k.a. what's their lifetime in the best possible case of never colliding with anything but air molecules?
what effects does symmetrical vs. undercambered have?
what effects does swept-tipped vs. straight tipped have?

A lower pitched prop might slow things down.

You might get a better answer over at the Drones and Model Aircraft Stack

@EricS A lower prop pitch will make the engine run faster. Only flight speed might suffer.

@PeterKämpf my RC modeling days predates electric motors. Typically we would up the diameter along with dropping pitch. A 10x8 might change to 11x7. Of course landing gear length needs to allow it. 10x8 seems pretty high pitch for a trainer.

I’m voting to close this question because it isn't about aviation, as defined in the help center, but belongs on https://drones.stackexchange.com/ instead.

@RalphJ While Drones.SE is a better place for this question, I don't think it is necessarily off-topic here. I have however voted to close as needs more focus.

New question is now: https://drones.stackexchange.com/questions/2090/influence-of-propeller-blade-shape-and-tip-shape-on-its-behaviour ... thank you all for your comments and answers!

Any fixed-pitch propeller has an efficiency that is a function of J = v/nd, where the advance ratio J is itself a function of airspeed v, angular speed n (in turns per second) and prop diameter d. For every pitch value, we have a parabola-like curve that has a maximum. The set of all maxima defines the enveloping curve, and that enveloping curve has itself a maximum.

That maximum of the envelope curve will correspond to the maximum of a given propeller pitch. Having previously defined the diameter and angular speed of your prop, and taking for v the airspeed for best L/D of your airplane, you now have the specs for the prop of highest efficiency...

From the "been there" file, you may wish to start with wood.  In the event of a nose over, breaking the prop first will put much less strain on the motor mounts and the rest of your model.
Also, get a prop balancer at your hobby shop and a rpm meter to check everything out before flying.
While you're at it, feel free to experiment a bit and talk with other flyers about prop choice.  Anything from a 10×5 to an 11×7 may be possible.  The first number is the prop length, the second is pitch.
Lower pitch, just like in real airplanes, gives better take off and low speed performance, while higher pitch is for more efficient cruising.
A straight wood 10×8 2 blade is a good place to start.  Once you get some experience, the next choices will be up to you.


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Piper J3 Cub: external lighting setup and history?
It's quite easy to find the external lighting setup (colors, location on the aircraft and frequency of navigation, anti-collision and landing lights) for big airliners online. I'm interested in the Piper Cub and have not been able to find much. Most videos on YouTube are shot in daylight or, if they were shot at night, tend to be of model airplanes.
From pictures I've found out:

navigation lights are of course red and green and positioned on the front-most, outer-most points of the wings as would be expected
(almost all) pictures show a red light atop the vertical stabilizer

What I've not been able to find out yet for sure with regard to still flight-worthy Piper Cubs:

is there (always/usually/sometimes) a red light at the bottom?
what's the red top and bottom (if any) lights' blinking frequency?
if there are strobe lights, where are they positioned and what is their strobing pattern?
are there Piper Cubs with landing lights or has the type always exclusively been VFR?

And in terms of history:

seeing as the Piper Cub was first built in 1937, last in 1994, and there was a gap from '83 to '88 with no production, how did its lighting setup change during that time? Where there any electrified Cubs produced at all, or is any electrification, including lights, completely custom?

I don't think the original cubs had an electrical system...

thank you Ron, I changed the last paragraph accordingly

I don't think J-3 Cub was made until 1994—the PA-18 Super Cub was. Of interest is addition of electrical system on the later.


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Can passenger plane do an aileron roll and fly upside down?
I've researched this topic and as far as I can tell any plane can fly upside down if it's already in this position. It just needs to be angled enough so that its wings are angled upwards. I believe Boeing 777 can do this although I can't find any video proof.
But my real question is whether Boeing 777 can do aileron roll. From my understanding plane needs to pitch upwards a bit to gain altitude and then start to roll sideways. While doing this it will loose all lift and starts falling downwards until it is upside down and gains lift again. What are the requirements for this? What is the minimum speed it needs to achieve before attempting the roll? Is Boeing 777 structurally sound to survive the attempt? I imagine it was not designed for this but is it possible?
And a bonus question: can you link me a video of any bigger sized plane doing that?

As long as it remains a 1-G maneuver, it shouldn't be a problem.

A loop has different structural and loading issues than a barrel roll and an aileron roll.  This question is a bit more specific than "aerobatics". The question also addresses inverted flight, which is more specific than "aerobatics."

In fact this has been done before.  A well documented case is of "Tex" Johnston rolling a 707.  In general airliners cannot do sustained inverted flight as they lack a fuel system (and lubrication system) for sustained inverted flight.
A barrel roll is readily executable. Youtube has a video of Tex Johnston doing a barrel roll.

Edit: I gave a quick answer and felt guilty about it. There is more to the story. The OP talks about aileron rolls. An aileron roll is a maneuver where the plane does not substantially change altitude. The G forces will be negative at some point, and it is more "violent" than a barrel roll.  A barrel roll is a maneuver where the plane is rolled about the longitudinal and lateral axis, if you will, a loop and a roll in one.  Properly executed the barrel roll is a positive G maneuver.
Years ago, when I was young and some old geezer was teaching me aerobatics, he would climb into the plane with a full cup of coffee.  My job was to get to the practice area, and execute some maneuvers, including barrel rolls in each direction, without spilling his coffee.

Technically, that was a 367-80, which is closer to the KC-135 than to the 707 (the KC-135 is basically a straight production run of tanker-equipped 367-80s, while the 707 is fairly extensively modified from the 367-80, with, among other differences, a significantly wider fuselage); they're still close siblings, though.

Structurally, only just. Design regulations stipulate that the aircraft must be able to withstand accelerations between -1 and +2.5 g. So structurally it could fly upside down but It would be at borderline structural failure. A barrel roll spends very little time at inverted and does not impose -1 g, and passenger planes can be seen doing this manoeuvre at airshows, a beautiful sight.

-1g is a very small margin: it means that you could in theory have sustained inverted flight, but any time you push the stick you put the aircraft outside of that margin.

Yes indeed, they need to be very careful when upside down :)

I think there is a discrepancy between "very careful" and "no problem".

You're absolutely right, I've amended the answer.


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Tiny margin between VFR cruise and over Class C?
Our class C airspace at KRDU has a 4400 ceiling. If I fly Westbound above the airspace at VFR cruise, I'm expected to be at 4500. Since this is a tiny margin and I don't want to bust into the airspace by accident, do some pilots fudge on the cruise altitude and create a larger margin for themselves, flying at say 4600? I'm a lower hour pilot and while that's no excuse to bust minimums, just asking what you all think. Yes yes, flying at 6500 is also an option but this was a rather short XC scenario, plus let's assume a cloud layer at say around 6000MSL. :-)

Usually when I fly over a Class-C, I call approach and just let them know I'm overflying. If they respond to you at all (with your callsign), you are cleared to enter, so flying at 4500 isn't a problem.

See https://aviation.stackexchange.com/q/15015/520 regarding Ron Beyer's comment.

I had a similar situation flying over the Class C at Albuquerque New Mexico.  Albuquerque's Class C goes up to 9,400 and I was flying VFR at 9,500.  In this case I was using flight following going from Las Cruces NM to Santa Fe NM and was handed off to Albuquerque Approach.  Albuquerque Approach simply told me to notify them if I needed to make any altitude changes to remain VFR.
I think most pilots would simply call Approach in this situation and let them know they are flying over their airspace.  You would need to know the correct altimeter setting anyway to make sure you are at the right altitude.

Correct me if I'm wrong, but you could simply get the ATIS to adjust your altimeter to? Still, I like the idea of notifying approach. Also: is there a good standard phraseology for relaying that particular piece of information? I don't mind just saying "FYI I'm flying 4,500 over the Class Charlie" but I'm also working on my ATC a bit more and want to sound more professional.

@saigafreak:  If you were not handed off through flight following I would tell approach that you are overflying the airfield at 4 thousand 5 hundred and give your intended route of flight.  You could get a close enough altimeter setting through ATIS although the ATIS would not be updated every time the altimeter value changed.  Also if you have dropped into the Class C due to turbulence you would not be in trouble since you are in contact with approach.

@saigafreak I would prefer to hear something like "Approach, N12345, 20 miles to the west requesting transition over the Raleigh Class Charlie at 4500" (and your aircraft type code if you didn't use your type as part of your callsign). That lets them know that 1) you aren't an inbound and 2) you aren't requesting flight following all the way, just a transition through the airspace. We would ALWAYS prefer to be talking to you instead of not, even if you're technically not in the Charlie.


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Can air-to-air refueling be done in compliance with the FAR's?
I am wondering if any FAR's would prohibit the air-to-air refueling of two civilian aircraft in the US. In our use case, the receiving aircraft would be custom-built, and it would receive fuel pumped from a portable tank temporarily installed in a Quest Kodiak turboprop with the cargo door taken off.
There's the umbrella "don't be reckless" rule, but if it's done in a controlled way, what laws might stop us?

What rules are you operating under? I assume that this isn't a "Part 91" flight... Is the receiving aircraft manned? Do you have protections to prevent the leaking of fuel unless a strong connection is made?

It would be a Part 91 flight, both aircraft would be manned. And we have a plan for fuel leak mitigation. If it sounds like a lot of trouble, it is for a record-breaking attempt.

I'm pretty sure there's no specific FAR against in-flight refueling but-- is it always impossible to know how the FAA will construe the reg against "careless or reckless operation" or whatever it says in any given case.

Thanks quiet flyer, what's an example of doing this without it being under part 91? In my heavily tracked professional flying career I never really paid attention to anything besides 91 and 135, embarrassingly

edit: i see that for a special airworthiness certificate, option no. 4 is "exhibition flights" which this could potentially fall under.

@quietflyer Because if it is something commercially, it wouldn't be Part 91...

Got it. I should've ruled that out in the initial question. Thanks!

I can't provide a definite yes or no, but I can discuss some of the FARs that will need to be considered. In most cases you have to consider three groups of FARs; covering aircraft, aircrew, and operations.
For the aircraft, they have to have an airworthiness certificate.
The Kodiak is certificated, but you have to address operating without the cargo door (may be approved) and if the temporary installation of your refueling equipment needs any approvals. Many temporary installations don't but since your refueling equipment will connect to another aircraft's fuel system it may need a 337 or STC.
You say the receiving aircraft will be custom built. That implies an experimental certificate. There are two, maybe three, different experimental certificates that you could theoretically apply. The first is Experimental-Amateur Built (E-AB). This could work if you are not a business and this effort is for personal educational purposes. It's the least restrictive, but is in a gray area of applicability. The second is Experimental-R&D. It would be applicable, but it's the most restrictive certificate as it limits you to just R&D flights and crew proficiency flights and it requires annual renewal. Experimental-Exhibition might apply, but it's usually limited exhibition flying of existing, non-certificated (typically ex-military) aircraft. In any of these, I would expect that you would need to include aerial refueling within the operating limitations and that means getting an FAA inspector to buy off on it.
For the aircrew, I expect the one potential issue is one of compensation. If everyone holds at least a Commercial certificate that would avoid any gotchas. The other issue may be meeting the FAA training guidelines for formation flying.
Flight operations would be subject to Part 91 and the operating limitations of the aircraft. I would expect that refueling operations would be limited to airspace 'not over populated areas.'
So, I expect it would be possible but it could be difficult getting the necessary approvals.

I would add consulting with people with military air-to-air refueling experience, not just simple formation flight, both for your safety and as a defense against a claim you were “careless or reckless”. ADM isn’t about eliminating risks; it’s about identifying and mitigating them.

I would start by contacting the ARTCC in whose airspace you would want to do this. Their Airspace and Procedures office should be able to assist, and get you in contact with the right people. They can also help, in the event that you get approval, with planning the airspace to use for the flight.
We used to do extensive airspace reservations for military flights, but we've done smaller scale stuff for civilians as well. We call the military ones "altitude reservations(ALTRV, pronounced Al-trav)", and generally use the term "waiver" for civilian use. It's mostly a difference in scale.
At ZDV, I've seen numerous civilian and government special flights involving similar requirements to aerial refueling (block altitudes, extended straight line patterns, formation flights, photo grids), but never refueling involving civilian aircraft.
I would think that the biggest issue might be insurance in case of a mishap.
Keep us posted, if you have any luck. I'd love to see this.

Yes, but you shouldn’t.
The FAA can allow nearly anything, with high enough level sign-off. But getting any sign-off out of the FAA can be an involved process, which can require significant domain knowledge. If you have to ask on here, you probably shouldn’t be doing it. Regardless of whether the FAR allows it, you’re going to need to manipulate FAA process to make that okay. If you don’t know how to do that, any answer you get on here is going to be too superficial or high-level to actually help.
It’s kind of like asking, “can I build a safe pedestrian bridge using toothpicks?” Obviously, yes: with enough time and money you can meet any performance requirement. And a question here might say “yes”, and even give you a broad overview of possible avenues. But if your main source of advice on method is stack exchange, you’re going to have a bad time. The format simply doesn’t allow transmitting enough of the knowledge base.
If you want to do this, you need to find a real-life expert on FAA processes and work with them. There are too many specifics.

"If you want to do this, you need to find a real-life expert on FAA processes and work with them. There are too many specifics"
.And that's why you start by contacting an ARTCC, and talking to their Airspace and Procedures office.If it can't be done, they'll tell you.

@atc_ceedee if you just want any yes-or-no answer, you’re right. If you want the answer to be “yes”, you should find someone to talk to them for you.


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"All exterior lights" when crossing a runway? Landing light, too?
AIM 4-3-23 (f) says "all exterior lights should be illuminated when taxiing on or across any runway".  AC 120-74B 7.h.2.c has similar words, except that it's limited to "crossing a runway".  Both conflict with other guidance, which would imply that turning on the landing light is a signal of your intent to take off.  Seems that it should be "all exterior lights except landing lights".  How do the pros interpret this?

This is discussed in this question: Should landing light be off during line up and wait position?
When crossing a runway, you do use landing lights along with everything else, and since you're on a taxiway, the presence of the landing lights in this case isn't understood as intent to takeoff since you aren't lined up on a runway.
For an aircraft that is at the end of the runway, lined up & in a position to take off, that's when the idea of "landing lights on = intent to take off" applies. When on-to-hold, everything else is on, mainly to make the aircraft visible in a "please don't land on me" sort of way, but the landing lights off provides an assurance to Tower controllers & anybody who is crossing the runway down-field that you really are planning to remain stationary right now. Then, with takeoff clearance, the landing lights come on. And if I thought that I'd been cleared to cross the runway but the other aircraft (lined up) has landing lights on, I have an earlier cue that he is powering up, so I'll hold short & ask the controller what's up. Matters not if he was wrong, I was wrong, or controllers were wrong; we're all better off if the taxiing aircraft doesn't enter the runway ahead of somebody accelerating toward takeoff speed, and the concept of "landing lights on = intent to takeoff" helps there.
And, conversely, if I'm starting to advance power for takeoff & somebody with all lights on seems to be rolling toward "my" runway, all those lights (A) helps me see him all the better, and (B) gives me a cue as to his intentions.  So I might reconsider continuing the takeoff until things get resolved.
Conflicts like that are (thankfully) quite rare, but because the consequences are so grave, keeping everybody aware of everybody else's intentions is a really good thing.


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What's the difference between an airplane that stalls nose down or just mushes in a stall?
What's the difference between an airplane that stalls nose down or just mushes in a stall?
I understand most GA planes go nose down after a stall, but some GA planes
don't drop their nose at all, they mush (they just drop in altitude).  How are these planes different?  Is their CM curve near horizontal, instead of negative, so that they fly almost neutral with little static margin? Or do they have a high horizontal tail volume and so with stick back, they just stay almost horizontal, or other?

https://en.wikipedia.org/wiki/Wing_twist

You are absolutely right that it has to do with the pitching moment (Cm) characteristics of the aircraft. Take a look at the sketch below illustrating three different pitching moment characteristics:

In all the cases, you can assume that the CLmax occurs around 12deg AOA (not presented here). Cm1 is the aircraft that would present a distinct nose-down upon reaching CLmax. This is also known as a pitch bucket, because of its shape, and is good for stall identification and recovery as the aircraft tends to un-stall itself.
Cm2 is the mushy case. With increasing aft column pressure, the AOA will continue to increase, while the airspeed may stagnate. No stall identification is naturally provided to the pilot.
Cm3 is anything from stick lightening to outright pitch up, depending on the aggressiveness of the instability. This is a common characteristic for high speed aircraft that have large LE sweep and the stall does not originate from the root of the wing.
As mentioned by Carlo, the degree of nose-down or nose-up would also be CG dependent. Aft CG would always have smaller pitch bucket and worse pitch up (if exist).

This is a good analysis of how static stability will affect stall characteristics. CG placement matters!  Definition of "mush" can be discussed.  It can be a semistalled aircraft nosing down in a shuddering mush (172),  or, you describe it, a low aspect wing (or tailplane) with a flatter near stall lift curve and nuetral static stability entering the max lift region with little fanfare and effect on performance.  This is why, 100 years ago, low aspect "squares" and deltas were popular tail designs.

@RobertDiGiovanni I'm not sure I would characterize aspect ratio with stall identification, since the aircraft level pitching moment is dependent on airfoil stall (straight tapered wing), spanwise stall (swept wing), downwash, and whether there are slats/flaps.

the difference in stall angle between high and low aspect wings will make your eyes pop.  Rather interesting, had I written "150 years ago" it would have been "popular sail designs".

@RobertDiGiovanni Understood. Vortex roll off is very different between the two cases, and more prominent in delta wings. This makes the lifting surface stall at higher AOA. But the OP was asking about stall characteristics and identification of an airplane.

I agree that planform and CG have a lot to do with it.  Many factors here.  I would add sharpness of leading edge and airfoil thickness.  Many trainers have rounded leading edges and thick airfoils, which make for a softer stall.  More on slats later (I want to help the Max 8).

That behavior is going to largely depend upon where the CG is located.  A fwd CG should offer a sharp break in the stall with the nose abruptly pitching down when the stall occurs.  An aft CG loads airplane will have a more demur, mushing and sinking stall and, in extremes cases where the CG is aft of the approved range, may be unrecoverable simply because both wing and tailplane have stalled and aerodynamic forces no longer permit the pilot to lower the nose to break the stall.

The behavior will vary from aircraft to aircraft, but a rearward set CG (great for fighters) will make it much easier to increase AOA (in straight and level (the kind of flight passenger carriers want to be in) flight), and pull the nose up into a full blown stall.  Forward set CG helps mitigate this effect by getting the nose to drop ballisticly before the wing fully stalls.  This is the "mush" that I enjoyed so much with the 172.  It unstalls it self (just let go of the yoke). Rear set CG may require down elevator to recover.  Warning buffet does help.

The simple answer is that it depends on the degree to which the airplane is stalled.  When an airplane is in the stalled regime the lift on the wings does not go to zero but usually gradually decreases (see graphic).  The horizontal stabilizer cannot support the weight of the nose on its own and needs a contribution from the wings to keep the nose from dropping.  If the wing is not producing enough lift to support the weight of the plane but producing enough lift to keep the nose in the air then you have a mushing stall situation.  If you stall more deeply, then the wing cannot support the weight (or more specifically the moment of force due to gravity) at the nose.

* Graphic taken from See How it Flies Website
In the Piper Cherokee that I fly the plane will break when I stall it aggressively (lots of back pressure on the yoke) but will mush if I stall it more gradually.

It's different planes and different flying conditions.  Picture a plane trying to do a quarter loop.  Without sufficient energy it will not make it to 90 degrees (pointed straight up).
Now, considering most GA planes have a thrust to weight ratio of around 0.20 to 0.25,  what affects how far into the "loop" we go before stalling?  Do we "mush" or pitch down sharply?
Energy is entry speed, so if we dive and then pull up at full power (zoom) we will go higher into the loop, maybe even completing it.  But if you don't make it to 90 degrees, the plane loses airspeed, stalls (with continued elevator deflection), sinks, and pitches sharply down.
Two factors contribute to pitch down. At full stall center of lift moves back to 50% chord and tail volume (as plane sinks) will "flip" the nose down.
Now picture entering the loop with no power or zoom, your plane does not nearly go as high to vertical, it simply loses airspeed and does a much gentler "mush".
Other factors include elevator authority.  The B-52 bomber has a comparatively "weak" elevator compared with an Extra 300. You don't want to stall one of those.
And light weight, which enables a much sharper loop entry.
Also placement of the CG.  Many trainer aircraft, including the Cessna 172, as set up for students with a forward CG (within limits)  to "weaken" elevator pitch up authority and encourage "mush".
But even with the 172, if CG is aft, stall characteristics can change dramaticly.


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Who runs the Air Navigation System (air traffic control) in Canada?
Who runs the Air Traffic Control system in Canada? Is it the government?

No. Unlike the United States where the Federal Aviation Administration (FAA) is both the operator and regulator of the air navigation system (ANS), these roles are separated in Canada and performed by two different parties. They are:

The regulator: Tranport Canada - Government of Canada
The operator: NAV CANADA

The Government of Canada passed the Civil Air Navigation Services Commercialization Act of 1996, which effectively sold the ANS to a newly-formed corporation, "NAV CANADA" for the price of $1.5 billion dollars. Since 1996, Transport Canada's role has changed to regulation and enforcement; they introduce, amend, revoke, and enforce the Canadian Aviation Regulations.
NAV CANADA become the sole operator of the civil ANS and is a private company whose revenues come from aviation customers and technology sales, not Government of Canada.
NAV CANADA operates the civil ANS using 7 Area Control Centres, 41 Control Towers, 56 Flight Service Stations, and 8 Flight Information Centres; military aerodromes and terminal control areas remained the responsibility of the Department of National Defence.


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Why haven't the remaining TRSAs been converted to Class C airspace?
The communication and radar equipment is already in place to provide radar services. ATC staff them. It seems like the biggest investment to get them converted to class C is charting. Why haven't they been converted in the 25 years since the airspace reclassification?

Possible duplicate of What is a Terminal Radar Service Area (TRSA) and what are its operational requirements?

@Dave Not even close to a duplicate.

while the question its self is not (in terms of the direct ask). The answer ultimately covers this question hence the dupe marking. If no one else feels it is a dupe it will remain open, it takes a few dupe markings before a question is closed as a permanent dupe.

@Dave That answer is 10% of what I'm looking for at best.

If that's true @MattYoung then I would suggest expanding your question. If others feel that the answer is covered and you don't there must be a way to express that.


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Does huge rotating AWACS radar affect flight characteristics?
I would think that having a huge mass spinning around should produce massive gyroscopic forces when turning or pitching.
There must be some clever way of minimising or eliminating the effects... How is it done?
(An example of the sort of thing I am talking about)

It certainly doesn't affect it a great deal - it's not much bigger than the engine pods, for a start.... and spins very slowly. That conspiracy theory shows a pathetic lack of knowledge, for something presented as authoritative (ignoring the caps lock and atrocious spelling)

Id think the aerodynamic forces of the radar dish would be much more of a factor than the rotation, which is pretty slow.

The current trend in AWACS design relies on AESA phased arrays anyways...

The AWACS surveillance radar components consist of multiple units grouped in 3 locations. Only the antenna array and its electronics are in the rotodome.
The receivers, radar processors, and  radar control & maintenance panel are in the main cabin.
While fiberglass and rubber make up the outside coating of the dome the inside is mostly hollow except for the antenna rays.
AWACS aircraft produce greater drag relative to that of  civilian jet liners. Therefore,  engines for AWACS require non recurring engineering(NRE) to handle the dual generator requirements of the aircraft.
In order to reduce its air drag during take-offs, and while flying endurance speed the dome is tilted down 6° at the front. The rotodome itself is hydraulically rotated. Remember, the Boeing 707/320 from which the Boeing E-3 Sentry was derived  can very easily carry a huge cargo load . Therefore, the addition of a 1.5- 2 ton rotodome makes no difference to an AWAC which in any case is not carrying more than 20 – 30 crew members.
Generally the radome scans at 6 revolutions a minute. When the radar is not operating the radome rotation rate is set at 1 revolution every four minutes ( In case of the E-3 it is 1 rotation every 10 seconds). Ergo, the torque that the rotodome produce is very low.

On the E2 Hawkeye the dish does not rotate very fast (ie, very slowly), and so the torque is probably negligible.  Usually the radomes are designed to help generate lift, and while certainly not as effective as a wing, do offset their own weight quite a bit.

Just an addition to this: It's not only about mechanical torque - the slow speed also prevents excessive aerodynamic forces from the spinning disk (ie one side of the disk generating more lift than the other)

@JonStory Do any AWACS aircraft have any moving parts exposed? I thought the rotating antenna was entirely contained within the radome, which is stationary with respect to the airframe.  So there wouldn't be any aerodynamic forces resulting from the rotation.

http://youtu.be/stof3n7vVPc this video shows it clearly rotates.

The radome definitely rotates on the E-3, I'm not sure about others
http://youtu.be/2tlHDpfIYWo?t=4m37s

@JonStory: According to Wikipedia, at least, the E-2 also has a rotating dome. But I'm curious about your comment about asymmetric lift from the dome. I would have thought it would behave more like a round wing rather than a helicopter rotor. I could see some Magnus effect, perhaps. Can you expound?

If it wasn't rotating, it would just act like a single wing (if it produces lift) or drag inducing blob (if it doesn't). But yes you've hit the nail on the head - the magnus effect actually contributes more to a roll and possibly yaw movement, but the "forward" side of the disk will produce more lift due to the higher relative velocity of the air over the surface. To an extent this is countered by the higher velocity of the air UNDER the dome (as it's the delta that really matters) but there's still a certain increase. Slower disk = less difference between the two sides, is the important point

@JonStory Thanks for the education!


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What rate of descent would kill you?
I was watching a video where a plane an MD-82 descended 18,000 feet per minute and crashed into a mountain.
The plane was not upside down/on its side/spiraling- it had about a 5 degree pitch up the whole time.
My question is: Would this rapid descent kill you, or at least make you pass out? What is the descent rate that would simply just make you go unconscious?

It's not the fall that kills you; it's the sudden stop at the end.

If the plane doesn't crash, the descent rate generally can't hurt you. If the plane crashes, the horizontal deceleration is likely to do far more harm than the vertical deceleration. That said, 18,000 feet per minute is pretty fast, like 180 knots, so unpressurized it could cause possibly ear & sinus damage. But those wouldn't kill you. A crash at 180 knots into a flat surface, will - either level flight into a cliff face, or straight down into flat earth or water.

I don't trust the accuracy of the described situation. A terminal vertical speed of 180knots in that sort of belly flop orientation doesn't quite pass the sniff test. The question its self is ok though.

You have heard of skydivers, right?

@Michael Hall: Didn't the guy who jumped from extreme altitude a few years ago actually exceed the speed of sound on the way down?  https://newatlas.com/alan-eustace-world-record-skydive-stratex/34423/  (Don't offhand know if the 822 mph/1,323 km/h was greater than the SoS at that altitude, though.)  And of course the Apollo astronauts reentered at ~25,000 mph.

@jamesqf - Fearless Felix Baumgartner. He surpassed Joseph Kittinger‘s record. Felix’s record was then surpassed by Alan Eustace. I hear someone is already preparing to break the record yet again. And, then there is the good call on the descent rate of astronauts on re-entry.

There is no descent rate that would directly kill you or make you pass out, the notion is nonsense from a physics standpoint. It may be possible to rupture eardrums from the pressure change in some people with pre-existing sinus and ear trouble. It would also be possible to die from the heat of air speeds over mach 2, but the exact speed depends greatly on the aircraft design and is not unique to a descent trajectory.

I always thought the whole notion of falling from a great height killing you before you hit the ground as complete and utter nonsense. The old wives tale of dieing from a heart attack during the fall is just that, an old wives tale perpetuated by the frequent retelling of it. Minus any pre-existing medical conditions, it is not a sound theory.
Skydiving proves this. After all, skydivers in extreme cases can reach terminal velocities of up to 300 mph.
However, you can lose useful consciousness due to hypoxia above 20,000 feet MSL without supplemental oxygen. The higher you are (and stay), the quicker it will happen.

+1, but are you really sure an otherwise healthy person can't suffer a heart attack or a similar condition from the extreme psychological stress of the fall and related knowledge of impending death? :-)

@TooTea They could certainly have one, sure, but the idea that they are dead when they hit the ground is absurd. Unless your heart explodes in your chest (unlikely if you are somewhat healthy), the time it takes for a heart attack to kill you will be more than the time it takes for you to reach the ground. You may be unconscious, but you are probably alive. The more probable theory is that people pass out (faint) rather than have some major medical condition mid-fall.

@TooTea - I can’t speak for someone who inadvertently finds themselves on the outside of an aircraft in flight or a tall building. As for skydivers, they typically are not of the personality type to suffer from resignation. During a canopy failure, they will spend every second of the rest of their airborne life working to get that chute open. Otherwise, they should not step out of the aircraft.

Sure, I meant the passengers of the example MD-82 in question, certainly not skydivers. Given how many people are afraid of flying, I would be surprised if everyone on board stayed calm all the way to the impact.

@TooTea - You make a valid point. Though, it can be argued that the person’s fear killed them, not the situation. And, certainly not the descent rate. Different people in the same situation, at the same descent rate, will have different reactions and outcomes. Conversely, the same person may have the same or similar reaction regardless of the descent rate. This makes the point not germane to the question about descent rate. It is not quantifiable.

Nobody said there are passengers. Could be cargo, could be empty other than pilots.

You are probably talking about the sensation that is felt when the aircraft starts accelerating downwards.
This cannot be arbitrary excessive and cannot go dangerously high. Most that it could be is the total weightlessness but even that much is not dangerous. Astronauts spend months in this condition.
While the sense of acceleration downwards may feel strong, it is just a sense. The acceleration sensor is in the inner ear. The generic nature of this sensor is the same as the one of sound and light sensor - it does not warn about the dangerous condition of your body, it just reports that it is detecting.


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How much could you increase lift using ailerons alone?
If a plane had ailerons that could be moved in the same direction, could the lift be increased by a non-negligible amount?

Well, that is pretty much what flaps do, so...

@MichaelHall … that's how flaperons came to be.

Related: What is the purpose of aileron droop used in some commercial airliners?


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Pilots use of the term "with" then a letter when talking to ground
In ground comms when taxiing a pilot may say for example:
"Kennedy ground, DELTA412 HEAVY, is in KILO-FOX, short of ALPHA with PAPA".
I get that this means they waiting a KF exit of the ramp just sort of the A taxiway but what does "with PAPA" phrase mean?

@Bianfable thanks I get it, "with" is simple shortening of the phrase "with information" and that refers to the ATIS information version they are working with.

Yes, the AIM 4-2-3 a. Initial Contact 3. says to use the following phraseology: “(ATIS) Information Charlie received”, but it is usually shortened to "with Charlie". (assuming US regulations, since your quote is from JFK)

By the way, this isn't just used when talking to ground, it's also used on initial contact with approach or tower.

If that was the exact phraseology, "papa" is the latest ATIS they've copied. (ATIS being a continuous broadcast of recorded aeronautical information, updated every half hour, or in case of a major change).
Listen to arrival ATIS Heathrow, and, at the very end, note the instruction to inform Heathrow on first contact.
Similarly, here's departure ATIS at JFK with similar instruction in the last line:

KJFK JFK ATIS INFO F 0251Z. 32004KT 10SM SCT140 BKN170 27/22 A3012
(THREE ZERO ONE TWO). APPROACH IN USE ILS RY 4R, RNAV Y RY 4L. DEPG RY
4L. NOTAMS... ILS RWY 22R OTS, RY 4L GS OTS. HAZD WX INFO FOR NY METRO
AREA AVBL ON FSS. SWAP IN EFFECT EXPECT REROUTES. BIRD ACTIVITY
VICINITY ARPT. NUM CRANES OPERATING AT JFK. READBACK ALL RWY HOLD
SHORT INSTRUCTIONS. ...ADVS YOU HAVE INFO F.

More related information about ATIS:
ATIS is renewed periodically, and "named" sequentially with ICAO alphabet (alfa, bravo, charlie etc.).
The reason for informing ATC which ATIS you have copied is that sometimes the ATIS changes after pilot has received it , and changes may contain useful information for pilot (in the question pilot had listened to ATIS named papa). ATC would then inform the pilot that "Current information is quebec". This would (should) prompt the pilot to listen to ATIS again.


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What type of chart is displayed on ATC radar screens?
I am looking to make an emulation of the radar screen familiar to Air Traffic Controllers, such as the pictures below. I have been having a very hard time finding what type of chart/map is being used. The closest I've been able to come is enroute low ILS charts and something called a Radar Video Map. What type of chart are these and where can I find more of them (for the US)?

Source: telegraph.co.uk

Source: pennlive.com

Source: reddit.com

Source: youtube.com

Hi Zero! Can you edit your post to include the images instead of just linking them, to proof it against link rot?

@JohnWiseman Sure, done.

It looks like the image in the video it's drawn with VATSIM VRC, more details here. Note there are different presentations depending on the type of control. It seems the one used here is emulating a TRACON.

Stelios is pointing you in the right direction: the video maps incorporate elements from the various published charts but are not a direct copy of any of them (and are not updated nearly as often).
In my experience at a TRACON in the United States:
There are many different maps we can select, including no map (a blank scope). Which information is separable (i.e. on distinct maps) can vary by facility.
In general order of importance, the maps can show:

The sector boundaries, both with surrounding controls and the boundaries of internal sectors. These can and do change with airport configuration (landing and departing runways).
The Minimum Vectoring Altitudes and prominent obstructions.
An "Emergency Obstructions" map displaying all known obstructions to assist in giving advisories to aircraft in distress flying below the MVA.
Any special-use airspace or TFRs.
Airports and ground-based navaids.
Runway final approach courses.
Instrument approach fixes.
SID/STAR/airway fixes.
Other fixes commonly used for coordination.
SID/STAR/airway routes.
Airspace class (B/C/D/TRSA).
Visual/geographic features like highways, train tracks, lakes and rivers, the coastline, etc.

Again depending on the facility, some of these are always visible—that is they are all combined on a single "base" map—and some may be toggled on or off. The older systems could only store six different maps; I'm not sure what the limit is for the current system but it's significantly more than that, at least 30.
I'm not experienced with the process of creating and editing the maps but they're vector images created by reference to lat/long coordinates, which allows the controller to zoom in or out and pan in all four directions while keeping the symbols where they should be relative to the ground and the radar site.
The video maps are not published, though the MVA charts are (with caveat of "not valid for navigation"). If you're interested in the maps used at a specific facility you will have to submit a FOIA request to the FAA.
If you're interested in just having the information to see for your own unofficial use I would look into VATSIM as @mins mentioned in a comment. They have hobbyist-level software that has already been developed to display video maps in a relatively realistic manner, and they have relatively realistic video map files to go with it. There's no need to reinvent the wheel, at least until you determine that the existing wheel doesn't work for you.

Thank you for your help! I think FOIA is my best bet, any ideas on how I should describe what I’m asking for? Is the video layers of ATC TRACON? Or something like that?

@Zero the term "facility STARS video maps" should be clear enough. You will likely have to submit a request for each individual facility you're interested in. For a Center use "ERAM" instead of "STARS." I don't know what file format they'll give you; I would at least ask if they have vector images (SVGs) available, but you might just get a JPEG of a scanned printout...

You might also reach out to VASAviation on YouTube—they obviously have some software they've developed and maps for it. (Those aren't FAA radar replays, only historical ADS-B tracks displayed on their own emulator.)

Yeah I did reach out and he told me he looked up “New York TRACON.” I did that and didn’t find anything like the one in the video, so…

Great answer, and it applies to Centers, as well, with the exception of #3. Our video maps don't have individual obstructions, but we have sectional charts overhead, that do. It's easy to visually correlate the two.

The question as it's phrased right now isn't clear if it's asking for the type of data displayed or the source of the data.
For the first case it has already been answered but I will reiterate for the sake of completeness:

Points (waypoints, airports, VFR points etc)
Navaids (VOR, ILS, NDB etc)
Runways
Coastline and border line
Control sectors
Range circles (for approach usually)
Airways and VFR routes
Radar tracks
Whatever the ATS unit wants

The last bullet is the most important as it answers the second question: you can't find these data. At least not easily. Some of them are in the country's AIP but that's not always freely available. Even then the AIP doesn't tell you what a controller sees as you don't need to know. The information is there but how it's displayed is another story.
Your best bet is to ask the unit you are interested to display. But again I wouldn't expect them to simply tell you "sure here it is". Take for example this question about Fayetteville TRACON. There is no answer (even mine) pointing to a ready to use data source. At some point while researching for that question I even came across the freedom of information act.
If this is for academic purposes though, it might be easier if the university makes the request.
Please note that my answer is based on my experience building my own radar simulator for HANSP and I know some of these aspects first hand.

You are right and wrong both. The screens show of course different information depending on the role of the controller, keep that in mind.
For example a sector controller responsible for high altitude traffic would see a different screen from his colleagues handling terminal traffic and the ground controller would see a different screen again.
The data is generally projected on a vector graphic of the area being controlled, so the controller has an indication of the geographical location of things. On top of that may be projected airways, waypoints, and things like that as relevant to the controller's responsibilities, and things like range circles as you see in the top image. Over that are projected the plots of individual flights, typically with information regarding aircraft type, speed, direction, altitude, and callsign.
The controller may be able to turn different layers of information on and off as needed to reduce clutter.
Different systems from different manufacturers and operating agencies may well have different information and other visuals, but that'd be a typical generalisation.

Thank you! That makes a bit more sense. However, I'm still wondering where I could get some of the layers you are speaking about, namely the boundaries and obstructions found in the one in the video I linked. Any ideas on that?

@Zero they're probably generated by the software on the fly based on semi-static information from places like the FAA and Eurocontrol. That's the same data printed charts (and those used in the electronic displays in aircraft) are ultimately derived from, but updated as needed rather than once every month or so.

Yeah you're definitely right. I'm really struggling to find anything that I can use to make maybe a program to compile it into something simple. Not sure how I can do this

@Zero these systems are multi-million dollar systems running on custom hardware. The data is probably not available to the general public, at least not easily. You'd have to contact say Eurocontrol or the FAA and ask them, maybe they have sample data sets you can use for that.

In the US, enroute ATC facilities use a combination of public  and proprietary data. Airports, low altitude routes, and high altitude routes are drawn using publically available information. Sector boundaries, range marks, extended center lines, etc are all custom designed and adapted to specific maps. The custom information is not readily available to the public.


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Does simulator time count towards Flight Time Limitations under EASA?
Does flight time in a FFS (Level D) count towards the maximum flying hours permitted under flight time limitations?
e.g. you spend 4 hours in a simulator. Do those 4 hours come off your maximum flying hours for the 3 day period, 7 day period, 28 day period, 84 day period and the year?
A reference under EASA would be great if anyone has it, please!

In the US, no.  The definition in Part 117 of Flight Duty Period (FDP) and Block Hours are specific to aircraft and "for the purpose of flight" and similar language.  While there can be contractual limitations on crew rest before a simulator training period, the FAA doesn't care. (Of course, time on duty, in the sim or classroom or otherwise all counts as time on duty that day if you then get into an aircraft to go fly.) We don't accrue FDP nor Block hour liability for time in the sim in FAA-land; dunno about EASA. (Probably depends on the exact language in those regs defining Block time.)

I think they only count for the duty portion of ORO.FTL.210 Flight times and duty periods.
From EASA ORO.FTL.105, on definitions, sim time is duty but not flight as flight duty period includes one or more sectors, and the definition of sector specifically mentions an aircraft.
Quoting EASA ORO.FTL.105,
‘duty’ means any task that a crew member performs for the operator, including flight duty, administrative work, giving or receiving training and checking, positioning, and some elements of standby;
‘flight duty period ('FDP')’ means a period that commences when a crew member is required to report for duty, which includes a sector or a series of sectors, and finishes when the aircraft finally comes to rest and the engines are shut down, at the end of the last sector on which the crew member acts as an operating crew member;
‘sector’ means the segment of an FDP between an aircraft first moving for the purpose of taking off until it comes to rest after landing on the designated parking position.


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Is it correct to say that inertia is the centrifugal force in a turn?
I came to this thinking using the law of inertia. If the centripetal force (aka. horizontal component of lift) is suddenly removed, the airplane will continue on its straight-line path. My additional thinking is the airplane wants to remain straight and level, it is the (unbalanced) horizontal component of lift that opposes it.

This question is entirely about physics, not aviation.

@Ralph, then so too is just about every question on this site about how airplanes turn, or balance of forces in a climb, or...

I said the word airplane tho

@RalphJ Physics is what makes aeroplanes fly. Let's delete all questions then, showing banking aircraft, aircraft in a climb, anything with flight dynamics since that is physics...

"I said the word airplane tho" ... okay, well, as long as we're talking about Physics 101 using an airplane as the turning object, it must be aviation related.  Is that all that's required to be on-topic here, "airplane"?  So if airplane #1 leaves city AAA flying toward city BBB at 490 knots, and airplane #2 leaves BBB flying toward AAA at 370 knots, and they meet 3 hours and 20 minutes later, how far apart are AAA and BBB? That question has two airplanes in it, so it must certainly be on-topic for Av.SE, right?

It's a convoluted way to think about it, but yes, the "fictitious force" commonly called centrifugal force is merely the effect of inertia, which is offset by centripetal force to create a curved path.

Oh the questions I can cook up when I ready my aerodynamics textbook. Thank you for the input!

A sympathetic commentator might call it a virtual force rather than a fictitious one.

@Frog Just quoting my high school physics teacher, from 1974.


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Will my CRI CRI twin engine plane fly if I replace the engine with a single 15hp gasoline engine?
I'm using a lighter materials to rebuild plane, to cut down plane weight to 56kg and a 1.2m 3blades propeller.

Welcome to Aviation Stack Exchange.  Please, take the [tour] and read through the [FAQ] to better understand how this Stack Exchange site works, and how to make this question better.

Are you asking about only having one engine on one side? That seems like a very bad idea...

With half the horsepower of the original, it will fly, but just barely, even allowing for a bit more thrust efficiency using a larger slower turning propeller.  Your airplane may be 15 kg lighter, but the pilot's carcass is as much or more as a share of the total weight.
So figure on maybe, at best, 55 percent of the original's available thrust with a better prop, which like with most light twins, removes probably 70-80% of the thrust available for climb.  The original could climb 1300 fpm, so the 15 hp version might manage 300-500 fpm, depending on how hot and high you were and how heavy the pilot is. Gain a little weight from excess beer and your climb margin might disappear completely if the weather is hot and you have a fun 3-wheel go-kart.
In any case, you wouldn't get me in a 15 hp Cri-Cri.

Having flown paramotors with around 15hp on tap, you may find that a max rate of climb in the tens of feet per minute might be ok on paper but it makes for an awful flying experience.


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Can I use Stihl fs250 engine for ultralight aircraft?
RPM 9000
Hp 2.2
Engine weight 6kg
Plane weight 40kg
Body weight. 70
Propellers(2blades) length 30 inches
Wings length 120 inches

Highly related (if not a dupe as answers on this question might answer yours): Can an ultralight aircraft fly with a 18hp engine?

A 2HP engine for an ultralight? Is this serious? Do you mean a drone?

The Lazair had two engines or 9.5 hp originally, and that was marginal.  You generally want 25 hp or better to have decent climb performance carrying an adult human.


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Will the electric motor work well in ultralight aircraft?
I'm trying to replace the 20hp gasoline engine in my ultralight aircraft (trike) to 10kw BLDC motor, asking to know if the 10kw BLDC motor will work
Motor+battery weight, is less than the actual engine weight.

two observations: 1.) 10kw, are only 14hp, so you might end up with an underpowered aircraft. 2.) https://www.youtube.com/watch?v=hp7JcmwKQcU

10kw is 13 HP.  If you were flying on 20HP, 13HP is going to be pretty doggy.  You need a 15kw motor. Hobby King sells a 15kw outrunner that would work, but if you want to use it direct drive with a decent sized prop you'd have to rewire the windings to optimize it for low RPM.  As a general rule, HP for HP and pound for pound, you will have 1/3rd the endurance of gasoline with electric power.  LioN batteries are really not adequate except for short flights or motorgliding.  They aren't any good for electric cars either, really, when you only get a 3rd of the range of a gas tank.

But, but, electricity has no emissions, so it has to be better, right???

Well, I suppose, if most electricity didn't come from nat gas and coal.  And nobody has even thought about the nightmare of disposing of millions upon millions of LioN batteries that wear out.  I think we're better off with gasoline until fully recyclable batteries with 3 times the current power density come along.  Then I'm all in.  That being said, I'd love to have an electric ultralight motorglider right now.  That's its niche, at this point.

@JohnK "nobody has even thought about the nightmare of disposing of millions upon millions of LioN batteries that wear out"
Absolutely nobody. Apart from tens of companies (just one example https://www.fortum.com/products-and-services/fortum-battery-solutions/recycling/lithium-ion-battery-recycling-technology )
plus: do you really think that refining produces no waste? the slop oil residual from refinery is a waste, that is then reprocessed to extract whatever is valuable from it ... exactly like from the exhausted lithium battery.

It might. This answer shows two graphs from a now dead link, from am article that concluded that a 20 hp electric motor does a better job at powering a hydraulic pump than a 50 hp combustion motor.
Range and endurance will be pretty poor though, unless you use that extension cord.

I'm attaching a gear to reduce the motor speed from 5500rpm to 2800rpm

What you need to do converting from gas to electric is to look at peak rpm for a given prop, and endurance.
HP comparisons may be meaningless because gas motors have much lower max rpm, and most aircraft need much more thrust taking off and climbing than cruising in level flight.
Also, extremely important to include glide ratio as a measure of thrust requirement for your airframe.  Generally, peak thrust requirement will be around 2x Vbg drag.  An electric motor should give you more, but endurance will be another major concern.
Recently a personal electric aircraft came to market that could hover, but with endurance of less than 1 hour!
So, please be aware there is no direct conversion and both gas and electric have their virtues.  It may be possible to keep the gas with an electric booster.  This would enable a much smaller gas motor.  Another approach would be the "diesel-electric", using a gas motor simply as a generator, greatly reducing battery size.
But for the personal ultralight, peak rpm (thrust) for your prop may be adequate with a lighter electric motor.

Thank you very much!


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Safe to use Volkswagen golf mk1 for my ultralight aircraft project?
Good day house, I'm trying to understand if I should use the Volkswagen  golf mk1 (60hp) engine for my ultralight projects..
All advise will be greatly appreciated.. ♥

Related: What are some of the differences between piston engines used in aircraft and automobiles?

You need to define what you mean by safe. As it is this is too broad and a matter of opinion.

Have you verified that the weight of your aircraft will still fall into the ultralight category with this engine?  I don't know the weight of this particular engine but my guess is that it's on the heavy side.

Are you trying to meet ultralight weight limits in a specific country, such as the US?

I'd be very surprised if even a stripped-down Golf Mk. 1 engine (even starter and alternator removed, magneto installed) would allow your ultralight to meet weight limits with pilot and fuel aboard.  The Golf Mk. 1 is a liquid cooled engine, and while I can't find a listing for the bare engine weight, it surely is much heavier than the air cooled two-stroke and four-stroke engines commonly installed on ultralight aircraft.  The coolant and lubricating oil alone would weigh almost half what a small Rotax engine would, and never mind the cast metal block and head, pistons, rods, and crankshaft, camshaft and cam drive parts.
If you really want to use an automobile engine, you might investigate how much power you can get from the small air cooled engines in a Citroen 2CV, Honda 500 or 600 Coupe, or other mini-car from the 1960s or 1970s.  The only liquid cooled automobile engines I can quickly think of that might come close to allowing you to make weight limits are the 1 liter 3 cylinder from the early Geo Metro (which was built by Suzuki for GM), or (but with many more weight-increasing bits) the 1 liter Eco-Boost engine from the Ford Fiesta of the past ten years or so.


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Could an aircraft have squashable wings that get thicker as it flies faster?
As I understand, for high speed subsonic flight a thicker wing is more aerodynamic, and at low speed, a thin wing is preferable. Could aircraft which range in speed from 180 to 620 knots (most commercial airliners) have wings which can compress to be thicker during high speed flight? This would be controlled either by a mechanical system to change its shape or just by the oncoming wind pushing it into shape.

What you mention seems to be called called variable thickness wing morphing. See those two papers for instance (if you have access) https://www.sciencedirect.com/science/article/pii/S0376042117301835 https://arc.aiaa.org/doi/10.2514/1.37073. I think this technology is currently limited to demonstrators, but I can't be sure of course.

Conventional lore has it the other way round, that a thick wing is better at 180 kt and a thin wing is better at 620 kt. What are your reasons for believing it is the other way round?

I took a free smithstonian course on aerodynamics and recall that thinner wings are better for low speed flight, and that this was figured out in the forties or something, when the jet engine allowed planes to fly much faster. I may be wrong


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Did every X-15 pilot become weightless when flying into the upper strato- and mesosphere?
The North American X-15 was aimed at breaking airspeed and altitude records. The flights that sought to achieve new airspeed records (Mach 5+) were rather leveled but the flights into the upper stratosphere, into the mesosphere and into space were parabolae. Since all of them were parabolic flights, was the pilot always weightless at peak altitude even during the flights that didn't surpass the 50 mi space border? In the stratosphere I think it depended on the rotational velocity of the plane whether they experienced weightlessness, negative gravity or "just" lower positive gravity after engine shutdown.
The same question also applies to any other high atmosphere parabola-flying plane such as Aleksandr Fedotov's MiG-25 reaching 37,650 metres (123,520 ft), Iven Kincheloe's Bell X-2 reaching 38,491 m (126,283 ft) and the SpaceShipOne and Two reaching sub-space altitudes.

Yes they did. Take away both rocket thrust and wing lift, and the plane goes into free fall. In this condition everything on board becomes weightless.
The pilot would feel only the light bursts of thrust from the small manoeuvring rockets, and the slow return of aerodynamic lift during re-entry.
You don't even need to go into outer space; check out the vomit comets used to train astronauts.


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Can a US pilot residing in the EU fly N-reg under IFR on a US PPL?
I am a US citizen living in the Netherlands, and I have an FAA PPL(A) with current IR as well as an EASA PPL(A) without IR.  I am currently trying to figure out my easiest path to IR conversion, as I do not have the required 50 hrs PIC time to do a direct conversion.  I know I can do the CBIR, but I'm wondering if I'm permitted to fly N-reg aircraft under IFR in order to build the required hours.  I've heard that as an EU resident I'm required to fly using both an EASA PPL and FAA PPL in an N-reg, and therefore I assume the answer is technically no.  Am I correct in this assessment?

How did you get a FAA IR without 50 PIC? FAR 61.65(g)?

@StephenS Sometimes FAA PIC time doesn't count for EASA purposes, perhaps that's what happened here.

@StephenS By 50h PIC I mean 50h non-dual PIC under an IFR flight plan, which is how EASA counts it.

Long story short, European residents apparently require an EASA license to operate a foreign aircraft, even if they also hold a foreign license from the country the aircraft is registered in.

European regulations are really difficult to pin down because implementation is delegated to member states, however it looks like as a resident in an EASA country you do need an EASA license to operate an N-registered aircraft based there. There are many online sources that say that, although they typically don't link to actual regulations. Several of them mention that you get a 12-month period to acquire the EASA license, during which you can still fly with your foreign license.
For example:
AOPA blog article:

The European Aviation Safety Agency, a pan-European regulator, had
passed a regulation some years earlier requiring that European
residents acquire a European equivalent license to fly an N-registered
aircraft in Europe. This requirement didn’t apply to nonresident
foreigners.

A UK Flight Examiner's website:

If your N-reg aircraft would be classified as an EASA aircraft if you
registered it under the G registration, AND it is based in the UK now,
you do need either an EASA licence to fly it or an EASA validation. If
you wanted to fly it outside the UK, you would need your FAA licences
too.

The underlying EASA regulation appears to be REGULATION (EC) No 216/2008, which says that it applies to foreign aircraft if the operator is based in Europe (Article 4, paragraph 1(c), emphasis mine):

registered in a third country and used by an operator for which any
Member State ensures oversight of operations or used into, within or
out of the Community by an operator established or residing in the
Community

Paragraph 2 says that the regulations apply to personnel too, it's not just about the aircraft itself:

[...] Personnel involved in the operations of aircraft referred to in
paragraph 1(b), (c) or (d) shall comply with this Regulation

The tricky part is that EASA leaves it to each member state to actually implement the regulations and sometimes they implement at different times (see comments in the AOPA article above). I couldn't find the Dutch regulations, but the UK regulations do confirm that only non-residents are exempt from European licensing requirements. Air Navigation Order, Article 149, emphasis mine:

This paragraph applies if the operator of the aircraft is neither
resident nor established in the European Union, and the person
acting as a member of the flight crew is the holder of an appropriate
licence granted or rendered valid under the law of the country in
which the aircraft is registered or the State of the operator.

(As an aside, the ANO article is written in a very confusing, double-negative construction, but it does line up with other sources.)
Because EASA delegates to each member state, the best way to get a definitive answer that applies to your situation is to contact the Dutch civil aviation authorities. When and if you do find out what the requirements are, it would be great if you would come back here and add your own answer to this question. There's surprisingly little definitive, sourced information available about this and a first-hand answer would be really helpful.

Thanks, and you've basically summarized what I thought I knew, but couldn't find anything definitive on.  I wasn't sure if there was some sort of exception for US citizens, for example, but haven't seen anything.  I've found people here have conflicting understandings of the FAA/EASA rules, including around conversion of licenses, and both the rules and enforcement seem in flux and inconsistent.

@rs_atl You're welcome. BTW, there's an FAA legal interpretation that you might want to see: Condell, 2009. It says that even if you get a Dutch license it's only valid in the Netherlands as far as the FAA is concerned. If you fly an N-reg aircraft to France (for example), France would allow that with your Dutch license but the FAA wouldn't. That means you have to be legal and current per FAA regulations too.


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what are some of the effects of breaking the sound barrier?
I have tried googling it, and nothing came up, please help! I am trying to figure out what happens after a jet/aircraft breaks the sound barrier.

Generally, loud noises

This seems to be a duplicate of What happens when an aircraft breaks the sound barrier?

What happens to what?  The airframe?  The pilot?  Observers on the ground?  Your question is pretty general, and there is all kinds of information about supersonic flight so I'm not sure what kind of key words you're searching on.

There is a loud boom that passes over the area.  It kind of makes buildings shake.  People I know who have been in planes while passing the speed of sound say the altimeter jumps.

If you have a mechanical clock inside with you, you can hear it tick.

@Mike Brass - "If you have a mechanical clock inside with you, you can hear it tick."  Only if it is in front of you.  If it is behind you the sound waves will not propagate forward to your ears.  Here is a link to a good demonstration of the effect:  https://www.youtube.com/watch?v=TklvFQsBxRM


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Best Glide with Flaps T/O in DA20-A1
The Diamond Katana DA20-A1 Manual says that the best glide angle can be achieved with flaps in the t/o position at 72kn at maximum weight.
My naive understanding would be that a flaps up position would always provide a better glide angle, because of the lower drag. So why does the Katana apparently have a better glide with flaps t/o?

The best glide flap setting is a matter of definition. If the base airfoil was optimized for high lift (like, say, the Wortmann FX63-137), the cruise flap setting would be some trailing-edge up position. If that is defined as 0°, and the take-off setting is the one for which the airfoil has originally been optimized, then it should not be too surprising that it allows the best L/D.
A high zero-lift drag coefficient, like from a fixed landing gear, will drive the optimum L/D to low speeds and a high lift coefficient. That is where the Wortmann FX63-137 excels and the reason why the optimum L/D of the Katana is at such a low speed. The Katana has inherited this airfoil from the H36 Dimona motorglider, and here it had been selected to meet the minimum sink speed requirement at that time for certification as a motorglider.
Airfoil trivia: The Wortmann FX63-137 has originally been designed for a human powered aircraft project. This explains its very high maximum lift at low Reynolds numbers.

Very detailed answer, thank you!


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What trailing edge flap design does the A350 use? Is it similar to the A380?
Both Airbuses have similar flap deployment based on some YouTube videos I have watched, just wondering if they both have the same flap design being "Single-Slotted Fowler Flaps".


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What is the dihedral angle of the A380?
It is understood that the A380 has a sweepback angle of 33.5 degrees and a taper ratio is approximately 0.3. However, what is the dihedral angle of this aircraft?